Application of isotope dilution for precise measurement of Zr and Hf in low-abundance samples and international reference materials by inductively coupled plasma mass spectrometry: implications for Zr (Hf)/REE fractionations in komatiites
Application of isotope dilution for precise measurement of Zr and Hf in low-abundance samples and international reference materials by inductively coupled plasma mass spectrometry: implications for Zr (Hf)/REE fractionations in komatiites
复制标题
应用同位素稀释通过电感耦合等离子体质谱精确测量低丰度样品和国际标准物质中的 Zr 和 Hf：对科马提岩中 Zr (Hf)/REE 分馏的影响
DOI：
10.1016/0009-2541(95)00041-j
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发表时间：
1995
期刊：
影响因子：
3.9
通讯作者：
R. Kerrich
中科院分区：
文献类型：
--
作者：
Q. Xie;R. Kerrich
幔源岩石中稀土元素和高场强元素的精确分析，对了解不同地幔储层的化学组成和地幔岩石圈的发育具有重要意义。对科马提岩和一些低丰度国际参考物质（即BIR-1）中的Zr和Hf进行了同位素稀释电感耦合等离子体质谱（ID-ICP-MS）研究，以评估之前通过ICP-MS使用外部校准获得的数据。纯元素标准品。同位素钉富集在91锆和179铪。使用的同位素比，91 Zr/90 Zr和179 Hf/178 Hf，实际上没有同量异位素干扰（例如，162 Dy 16 O和163 Dy 16 O的形成率为0.4- 0.6%，换算成179 Hf/178 Hf测量值的不确定度为±0.02%）。质量偏差，显示减少轻质量的响应，是不敏感的分析物溶液浓度范围内的锆0.08-1.8 ppm，和0.003-0.051 ppm的铪。参考未加标对应物中Zr和Hf的天然同位素比，校正加标样品的质量偏倚。未知样品和标准样品中Zr和Hf的结果与先前使用外部校准通过ICP-MS获得的结果一致，但精度有所提高。BCR-1中Zr的精密度（184 ppm，0.005% RSD）与通过热电离质谱法获得的精密度相当。结果证实了前人报道的非贫铝科马提岩中Zr和Hf相对于MREE的正异常或零异常，而非贫铝科马提岩中Zr和Hf相对于MREE的负异常，这对地幔熔融深度和太古代地球动力学具有重要意义。
Precise analysis of all REE's and HFSE's in mantle-derived rocks is critical to understanding the chemical compositions of different mantle reservoirs and the development of mantle lithosphere. An isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) study of Zr and Hf in komatiites and some low-abundance international reference materials (i.e. BIR-1) was undertaken, in an effort to evaluate previous data obtained by ICP-MS using external calibration with pure elemental standards. Isotopic spikes enriched in91Zr and179Hf were employed. The isotope ratios used,91Zr/90Zr and179Hf/178Hf, are virtually free of isobaric interferences (e.g., formation rate of162Dy16O and163Dy16O is 0.4–0.6%, translating into uncertainties in measured179Hf/178Hf of ∼ ±0.02%). Mass bias, showing reduced response for light masses, is insensitive to analyte solution concentration in the range 0.08–1.8 ppm for Zr, and 0.003–0.051 ppm for Hf. Mass bias for spiked samples was corrected with reference to the natural isotope ratios of Zr and Hf in unspiked counterparts. The results for Zr and Hf in unknowns and standards are in good agreement with previous results obtained by ICP-MS using external calibration, but with improved precision. Precision for Zr in BCR-1 (184 ppm, 0.005% RSD) is comparable to that obtained by thermal ionization mass spectrometry. The results confirm previously reported positive or zero normalized anomalies of Zr and Hf relative to MREE's in Al-undepleted komatiites, but negative anomalies in Al-undepleted komatiites, that have significance for the depths of mantle melting and Archean geodynamics.